Avocado Oil Extraction in Leguruki IDDS 2014 - Tanzania
Abstract This paper presents the progress on developing an appropriate avocado oil extraction process for rural villagers in Leguruki, Tanzania. Avocados are a plentiful but low-value resource in Leguruki, with no perceived use except for consumption. Through discussions with users, avocado oil was identified as a potentially valuable product. Three initial avocado oil press prototypes were developed and brought to Leguruki to gather user feedback and explore community interest. While all three prototypes successfully pressed oil, a fourth prototype was developed that explored a new direction, rather than expanding upon any of the three previous directions. In addition, a solar dryer was developed, as drying avocado was a critical but unaddressed part of the oil pressing process.
Context Background This project was started at IDDS 2014 - Tanzania. The village of Leguruki was selected to be one of IDDS’s local community partner villages, and was identified to have an overabundance of avocado. A team of five IDDS participants was faced with the open-ended task of working with Leguruki to capitalize on the amount of unused avocado in the area. The project continued at IDDS for five weeks, and is still under development by team members who remained in Tanzania post-IDDS.
Community Description Located 48 kilometers from Arusha town, Leguruki is the administrative ward of Meru District in the Arusha region of Tanzania. Leguruki village is the name of the capitol village in the Leguruki ward. Leguruki has a population of 17,000 people, predominantly from the Meru tribe. Most citizens are small-scale farmers that grow various crops and fruits. The principle crops are coffee, maize, and beans, and the most commonly grown fruits are avocados, oranges, papayas, guavas, and bananas.
Design Process Problem Framing Statement Avocados in Leguruki are a plentiful resource but have very little value, selling for as little as 25 TZS per avocado when sold in bulk. They are under-utilized as well: their only perceived use is consumption, and so approximately 50% of avocados cannot be sold or eaten and consequently end up being wasted.
Value Proposition We believe that avocado oil extraction will address many of the problems faced by villagers in Leguruki, as avocado is a versatile and high value product. As cooking oil, it is comparable to olive oil, both in cost and quality. It can also be used in cosmetics, such as soap, shampoo, and lotions. Currently, an average household in Leguruki spends 400 TSh on cooking oil per day, totaling 146,000 TSh per year. In the short-term, we believe that an avocado oil press will provide value by allowing households to extract their own oil and cut down on other cooking oil costs. In the long-term, we hope that Leguruki can access markets to sell the oil in, and also earn money from selling products made from processed avocado oil.
Summary of Design Process Prior to the first visit to Leguruki, research was conducted on alternative uses of avocados and on other avocado producers. This research was important as it allowed us to gauge users’ understanding of avocados and also to gauge users’ interests in different processes. Our first trip to Leguruki lasted 4 days and was centered on gathering information about users. Interviews with users typically lasted 15-20 minutes. The bulk of each interview focused on the user’s current state with respect to avocado growing. This included asking about how many avocados they had, how they were harvested, what they did with the harvested (and notharvested) avocados, and if they had heard of any other alternative uses. Contact info was taken down and users were invited to a community presentation, which was held on our last day. After synthesizing the information gathered in the interviews, we framed the problem using a problem framing statement and tree. We then created sketch models, which we presented to the community on the last day. At the presentation, we gathered feedback on the sketch models to ensure that we would be working toward a solution that was desired by the community. The feedback was overwhelmingly in favor of creating an avocado oil press. Upon returning to Leguruki, we began brainstorming ideas for extracting avocado oil. We simultaneously ran small experiments where we attempted to dry avocado. We finally settled on three ideas (hammer press, standing press, and jack press) and built prototypes for these ideas. We decided on three ideas rather than one so that we could get feedback on users’ desired pricepoint, since we were unsure how users valued price and convenience.
Upon arriving in Leguruki, we procured avocado and laid it out on tarps to dry. The avocado was left out for three days, and rotted instead of dried. From this, we identified drying as a critical part of the oil extraction process that we would have to address. In the mean time, we dried avocado by cooking it down and boiling off the water, which decreased the quality of the oil and also discolored it. We used the dried flesh to test our prototypes and demonstrate them to users. Feedback was again positive, but users were divided on price. One group, mostly men, were willing to pay upwards of 100,000 TSh for an oil press, and expressed interest in using it to create a small business. The other group, mostly women, quoted prices between 15,000-25,000 TSh. After returning to Arusha, we again divided ourselves to create multiple prototypes. One prototype was a solar drier, and the other (lever press) was a different kind of oil press that used a long lever to increase the force provided by the user. During the prototyping process, we dried avocado in a solar drier that was kept at the workshop. We varied the drying process by cutting the avocado into pieces, rather than a mush. The result was mostly unsuccessful, as the pieces dried on the outside but not the inside.
Analysis and Experimentation Oil Pressing 9 avocados were dried and then pressed, producing 340g of oil. The density of avocado oil (0.92g/ml) was taken from kn own data tables and used to calculate the volume of oil extracted per avocado: 41ml of oil per avocado.
Drying We first attempted to dry mashed up avocado flesh while in Arusha. O ur first test was a failure, due to unforeseen circumstances wherein wild dogs ate all of our avocado. During the second test, mashed avocado was layered and placed in an oven to dry. The avocado mash was layered to include 4 different thicknesses. This test partially failed, due to unforeseen circumstances wherein the kitchen’s chefs re-spread the avocado flesh to form a single, uniform layer. However, this test did allow us to validate that oil can be extracted from dried avocado using very little force (such as pressing the dried flesh between fingers). The third drying experiment was conducted in Leguruki. 20L of mashed up avocado was spread onto a 20 foot tarp and left to dry in the sun for 3 days. This test also failed to produce dried avocado, but succeeded in creating 20L of moldy, noxious-smelling, rotten avocado. Part of the reason this drying method didn’t work was that Leguruki only gets around 4-5 hours of direct sunlight during the winter months (such as July) and otherwise is overcast and damp. This drying experiment was significant because it clarified the need for a drying technology. When sun drying failed, we experimented with boiling mashed avocado. While effective, it discolors the oil and gives it an unpleasant taste. It is also requires a lot of time and fuel, which led us to conclude that cooking down avocado is not a long-term solution for oil extraction. The final drying experiments were conducted in Arusha. Avocados were cut into pieces (large chunks the size of an orange slice, and smaller pieces approximately a third of the size of the larger chunks) and placed on trays inside of an up-draft solar dryer. These pieces were left to dry for three days. The pieces were dried on the outside, but did not sufficiently dry on the inside. Several were starting to get mild as well. Still, this experiment was promising because it
suggested that drying is feasible if adjustments were made to the drying technology and process.
